Plasma glucose alone does not predict neurologic dysfunction in hypoglycemic nondiabetic subjects

Hypoglycemia-Induced Changes in the Electroencephalogram: An Overview

Hypoglycemia is defined by an abnormally low blood glucose level. The condition develops when rates of glucose entry into the systematic circulation are reduced relative to the glucose uptake by the tissues. A cardinal manifestation of hypoglycemia arises from inadequate supply of glucose to the brain, where glucose is the primary metabolic fuel. The brain is one of the first organs to be affected by hypoglycemia. Shortage of glucose in the brain, or neuroglycopenia, results in a gradual loss of cognitive functions causing slower reaction time, blurred speech, loss of consciousness, seizures, and ultimately death, as the hypoglycemia progresses. The electrical activity in the brain represents the metabolic state of the brain cells and can be measured by electroencephalography (EEG). An association between hypoglycemia and changes in the EEG has been demonstrated, although blood glucose levels alone do not seem to predict neuroglycopenia. This review provides an overview of the current literature regarding changes in the EEG during episodes of low blood glucose.

Clinical review: Strict or loose glycemic control in critically ill patients--implementing best available evidence from randomized controlled trials

Glycemic control aiming at normoglycemia, frequently referred to as 'strict glycemic control' (SGC), decreased mortality and morbidity of adult critically ill patients in two randomized controlled trials (RCTs). Five successive RCTs, however, failed to show benefit of SGC with one trial even reporting an unexpected higher mortality. Consequently, enthusiasm for the implementation of SGC has declined, hampering translation of SGC into daily ICU practice. In this manuscript we attempt to explain the variances in outcomes of the RCTs of SGC, and point out other limitations of the current literature on glycemic control in ICU patients. There are several alternative explanations for why the five negative RCTs showed no beneficial effects of SGC, apart from the possibility that SGC may indeed not benefit ICU patients. These include, but are not restricted to, variability in the performance of SGC, differences among trial designs, changes in standard of care, differences in timing (that is, initiation) of SGC, and the convergence between the intervention groups and control groups with respect to achieved blood glucose levels in the successive RCTs. Additional factors that may hamper translation of SGC into daily ICU practice include the feared risk of severe hypoglycemia, additional labor associated with SGC, and uncertainties about who the primarily responsible caregiver should be for the implementation of SGC.

An overview of hypoglycemia in the critically ill

Hypoglycemia is a common and serious problem among patients with diabetes mellitus. It is also perceived as the most important obstacle to tight glucose control using intensive insulin therapy in critically ill patients. Because glucose is an obligatory metabolic fuel for the brain, hypoglycemia always represents an emergency that signals the inability of the brain to meet its energy needs. When left untreated, hypoglycemia can result in permanent brain damage and ultimately, death. In the context of critical illness that limits endogenous glucose production and increases glucose utilization, inadequate nutrition, or insufficient provision of glucose, intensive insulin therapy is the most frequent cause of hypoglycemia. Neurogenic and neuroglycopenic symptoms of hypoglycemia can remain unknown because of the underlying critical illness and sedation. Thus, close and reliable monitoring of the glycemic level is crucial in detecting hypoglycemia. In prospective randomized controlled studies comparing the effects of two glucose regimens, intensive insulin therapy aimed to reach strict glucose control (<110 mg/dl) but increased the incidence of severe hypoglycemia (<40 mg/dl) by four- to sixfold. Severe hypoglycemia is statistically associated with adverse outcomes in intensive care unit patients, although a direct causal relationship has not been demonstrated.

Insulin infusion protocols for critically ill patients: a highlight of differences and similarities

OBJECTIVE

To discuss the major differences and similarities among the currently published insulin infusion protocols (IIPs) for critically ill patients.

METHODS

IIPs were identified by searching MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials. The reference lists for all retrieved protocols were also reviewed to identify any IIPs that were not surfaced with use of our initial search strategies. The major differences and similarities among the IIPs were identified and examined. In addition, strategies for successful implementation of IIPs were outlined.

RESULTS

Our search strategies retrieved 17 IIPs. Currently, no published studies have compared one insulin protocol with another. The major differences or similarities among the published IIPs were in the following areas: patient characteristics, target glucose level, time to achieve target glucose level, incidence of hypoglycemia, rationale for adjusting the rates of insulin infusion, and methods of blood glucose measurements. Because of variations in the definition of hypoglycemia, methods of blood glucose measurement, and types of blood samples used, some comparisons across the protocols were difficult. Use of a multidisciplinary team and gaining administrative support are crucial for addressing issues and provision of necessary resources for implementing a protocol for "tight" glycemic control in critically ill patients.

CONCLUSION

Clinicians should evaluate the type of patients in their critical care units, the mean baseline glucose levels, and the available resources to determine the most appropriate and practical IIP for their institution.

Achieving tight glycaemic control

The implementation of tight glycaemic control (TGC) is becoming accepted best practice within intensive care units throughout the world. It is recommended by the Surviving Sepsis Campaign and is included in the sepsis care bundle. The major impact of TGC is currently thought to be associated with reduced morbidity and mortality. The process of achieving TGC is, however, not without risk. In particular, the need for frequent, accurate blood glucose measurement and the possibility of prolonged, unrecognised hypoglycaemia are of concern. There is also the potential for patients who exhibit significant insulin resistance to require the administration of large amounts of insulin. The transfer of patients from the intensive care unit to the operating theatre or for computerised tomography during intensive insulin therapy is also hazardous. The purpose of this paper is to describe a series of nurse led pilot studies which aimed to introduce the process of TGC whilst maintaining patient safety. The results demonstrate the effectiveness of a staged approach and the achievement of TGC.

Intensive insulin therapy in intensive care: an example of the struggle to implement evidence-based medicine

Schultz and colleagues discuss the factors hindering implementation of intensive insulin therapy.

Preparing the azotemic diabetic patient for surgery

Azotemic diabetic patients have more risk of complications during or after surgery than those without diabetes and azotemia. These complications include infection, excessive bleeding, cardiovascular events, and electrolyte imbalance. The appropriate preoperative evaluation, measures to be taken to avoid the complications, and how to adequately manage blood sugar during surgery is discussed.